In Big Data modeling, what does "schema on read" mean?

"Schema on read" refers to the practice where the structure of the data is interpreted and defined at the time of data retrieval, rather than during the initial data ingestion process. This approach allows for greater flexibility, as it enables users to adjust how they want to view or analyze the data when they access it, accommodating various analytical needs or changes in requirements without having to alter the underlying data itself.

In large datasets where the nature of the data can be diverse and unpredictable, this method of dynamically interpreting the schema allows for quick and efficient querying and analysis, particularly suited to environments like big data where traditional schema enforcement can be limiting.

This concept contrasts with approaches like "schema on write," where the data must fit a predefined structure before it is stored, potentially leading to constraints and complexities in data management and modifications.